This is an analysis for presence of faces in the whole Season 1 of NetFlix's TV series House Of Cards.
Small timelines on the left show number of faces per second for the entire duration of an episode.
The big interactive chart on top shows the same for Episode Three. Other episodes were not made interactive. Hover the mouse over or tap on it, and relevant faces for that point in time should appear below.
The chart is compressed, so one can't really see the gaps in which no faces were detected. To compensate and offer a better experience if one hovers over such a gap, the next point in time with faces in it is shown, so there is always something below the chart.
I recommend moving mouse pointer or tapping your finger slowly over the portions with higher number of faces to see a bigger number of them.
There's no indicator of absolute number of faces on the timelines for several reasons. First, the face recognition technology I used (OpenCV) works well enough, but is prone to some errors, so it gives false positives, or it doesn't recognize a face when it should.
Then, some faces are recognized only for a brief period of time. For example, there's a scene in church with many people in it, and many faces were recognized for one frame only in the whole second.
At the time, it seemed a reasonable conclusion that faces that are recognized in just a few frames per second, may be false positives. So, to give a sense of face detection reliability,
I counted the number of frames per second that each face was recognized in. Thus three different line colors in the timelines.
Legend█ low reliability (1 frame in a second)
█ medium reliability (3 -5 frames in a second)
█ high reliability (5 or more frames in a second)
More information in the blog post.